Instead, the Marine Corps put them into a kind of decompression chamber, keeping them at Camp Pendleton for 90 days with the hope that a slow re-entry into mundane daily life would ease their trauma.

The program was just one of many that the military created as it tries to address the emotional toll of war, a focus that is getting renewed attention as veterans struggling to adjust back home are accused of violent crimes, including murder.

While veterans are no more likely to commit such crimes than the general population, the latest cases have sparked a debate over whether they are isolated cases or a worrying reminder of what can happen when service members don’t get the help they need.

“This is a big focus of all the services, that we take care of our warriors who are returning because they have taken such good care of us,” Navy Secretary Ray Mabus said, pointing out that tens of thousands of veterans return home to lead productive lives.

Some, however, fall on hard times, getting into trouble with the law. Others quietly suffer, with their families and friends trying to pull them out of a depression.

In the latest high-profile criminal case involving an Iraq war veteran, a former Camp Pendleton Marine is accused of killing four homeless men in California. His family said he was never the same after his 2008 deployment. In Washington state, an Iraq War veteran described as struggling emotionally killed a Mount Rainier National Park ranger and later died trying to escape.

Suffering from combat stress is an age-old problem. What’s new is the kind of wars that troops fight now. They produce their own unique pressures, said psychologist Eric Zillmer, a Drexel University professor and co-editor of the book “Military Psychology: Clinical and Operational Applications.”

The war on terror “is very ambiguous, with no front lines, where you can’t tell who the enemy is. During the day, he may be a community leader and, at night, a guerrilla fighter. You never know when an assault takes place. It’s very complicated, and people feel always on edge,” he said.

Add to that, multiple deployments that tax the central nervous system, said Zillmer: “The human brain can only stay in danger mode for so long before it feels like it’s lost it. It gets exhausted.” He compared going into combat like “diving to the depths of the ocean and when you have to go back to the surface you have to decompress.

“It’s the same process,” he said. “It’s almost a biological process.”

A 2009 Army report concluded that the psychological trauma of fierce combat in Iraq might have helped drive soldiers from one brigade to kill as many as 11 people in Colorado and other states. The study found the soldiers also faced “significant disruptions in family-social support.”

The military’s stubbornly high suicide rate has proven that more help is needed, and that is why it has been investing in helping troops transition back from war zones.

Few units know war’s pain more than the 3rd Battalion, 5th Marine Regiment. The Camp Pendleton battalion nicknamed “The Dark Horse” lost 25 members in some of the heaviest fighting ever seen in Afghanistan. More than 150 Marines were wounded. More than a dozen lost limbs.

The Marine Corps brass, concerned about the traumatic deployment’s fallout, ordered the entire 950-member unit to remain on the Southern California base after it returned home. The 90 days was the same amount of time crews aboard war ships usually spend upon returning home.

During that time, the Marines participated in a memorial service for their fallen comrades. They held barbecues and banquets, where they talked about their time at war. Before the program, troops would go their separate ways with many finding they had no one to talk to about what they had just seen.

Mental health professionals are monitoring the group, which has since scattered. They say it is too early to tell what kind of impact keeping them together made. Combat veterans believe it likely will help in the long run. The Marines have ordered combat units since then to stick together for 90 days after leaving the battlefield.

“They share a commonality because they’ve gone through the same thing, so it helps them to come down,” said Maj. Gen. Ronald Bailey, the commanding general of one of Camp Pendleton’s most storied units, the 1st Marine Division.

“I can tell you from experience that this will help,” said Bailey, who served in Iraq and Afghanistan.

The new practice is one of a slew of initiatives ushered in by the new commandant, Gen. James Amos, who has made addressing mental health issues of Marines a top priority. He was concerned by the branch’s suicide rate, which has ranked among the highest of the armed services.

Commanders have tried to remove the stigma that seeking help is a sign of weakness. The Marines have set up hotlines and designated psychologists, chaplains and junior troops to identify troubled troops. “We’ve been in this 11 years and the medical staff and Marine officials are better educated now on dealing with combat stress,” Bailey said.

All service members also now undergo rigorous screening of their mental stability both before and after they go to battle.

While Veterans Affairs and Department of Justice have said veterans don’t commit more crimes per capita than others, the VA has launched efforts to help veterans in trouble with the law receive help rather than just be locked up.

Since 2009, the VA has had a legal team review cases to see if the best remedy is treatment instead of incarceration. States also have been establishing special veterans courts to do the same. Some say combat stress is also being used by criminals trying to get a lighter sentence.

Veterans agree the military has made great strides in the past few years but they say the help has come too late for many.

Paul Sullivan, executive director of the Washington, D.C.-based National Organization of Veterans’ Advocates, said the military only started administering medical exams of service members before and after deployments to Iraq and Afghanistan in 2007 to identify problems early so they can be treated more effectively and less expensively.

“It’s good their implementing it now, yes, however, what’s the military going to do with all of the veterans the military didn’t examine?” he asked. “That’s the problem.”